Evaluating the destabilization susceptibility of active rock glaciers in the French Alps

• Published in: The Cryosphere
• Main Authors: Marcer, Marco, Serrano, Charlie, Brenning, Alexander, Bodin, Xavier, Goetz, Jason, Schoeneich, Philippe
• Other Authors: Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS), Pacte, Laboratoire de sciences sociales (PACTE), Sciences Po Grenoble - Institut d'études politiques de Grenoble (IEPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Department of Geography and Environmental Management Waterloo, University of Waterloo Waterloo
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: geo; envir; permafrost; The Cryosphere
• Online Access: https://doi.org/10.5194/tc-13-141-2019; https://hal.archives-ouvertes.fr/hal-02011802/file/Marcer%20et%20al.%20-%202019%20-%20Evaluating%20the%20destabilization%20susceptibility%20of%20a.pdf; https://hal.archives-ouvertes.fr/hal-02011802

International audience In this study, we propose a methodology to estimate the spatial distribution of destabilizing rock glaciers, with a focus on the French Alps. We mapped geomorpho-logical features that can be typically found in cases of rock glacier destabilization (e.g. crevasses and scarps) using orthoimages taken from 2000 to 2013. A destabilization rating was assigned by taking into account the evolution of these mapped destabilization geomorphological features and by observing the surface deformation patterns of the rock glacier, also using the available orthoimages. This destabilization rating then served as input to model the occurrence of rock glacier destabilization in relation to terrain attributes and to spatially predict the susceptibility to destabilization at a regional scale. Significant evidence of destabilization could be observed in 46 rock glaciers, i.e. 10% of the total active rock glaciers in the region. Based on our susceptibility model of destabilization occurrence, it was found that this phenomenon is more likely to occur in elevations around the 0 degrees C isotherm (2700-2900ma. s.l.), on north-facing slopes, steep terrain (25 to 30 ffi) and flat to slightly convex topographies. Model performance was good (AUROC = 0.76), and the susceptibility map also performed well at reproducing observable patterns of destabilization. About 3 km(2) of creeping permafrost, or 10% of the surface occupied by active rock glaciers, had a high susceptibility to destabilization. Considering we observed that only half of these areas of creep are currently showing destabilization evidence, we suspect there is a high potential for future rock glacier destabilization within the French Alps.